The buttons are detachable for frequent laundering, as one
'sweats' more in the summer months.........
The lack of lining made me think WWII as I've seen Canadian ]
jackets made in exactly the same way.
I'm not sure; the buttons are definately Army Service Corps ones, which must make it (due to corps amalgamations) Pre 1918
I have an identical tunic. A 4 button kd tunic, unlined with detachable buttons. I've always assumed mine was early ww2 issue as the ww1 tunics had 5 buttons.